| 摘要: | 台灣地區處於西北太平洋地區颱風及梅雨侵襲的主要路徑，屬於極易受到天然災害影響的區位。世界銀行2005年刊行之 Natural Disaster Hotspots – A Global Risk Analysis 指出，台灣同時暴露於三項以上天然災害之土地面積與面臨災害威脅之人口為 73%，而暴露於兩項以上天然災害之土地面積與面臨災害威脅之人口為99%，屬於全世界災害高風險的區域。由於近年來全球氣候異常，因此極端災害型天氣發生機率增加，其中如2008年之緬甸納吉斯（Nargis）災害、2009年台灣的莫拉克風災害、2010年巴基斯坦洪災以及2010 年加州的水災，其災害規模與極端降雨量均超出該國的歷史災害經驗，也為該國的政府與人民帶來巨大的損失。因此目前極端降雨的情況下，因此官方預報很難掌握此方面的趨勢，而準確的颱風及梅雨降水預報是民眾的期望，也一直是科學界努力之目標。由於颱風及梅雨主要的生命期多半是處在廣大的洋面上，而這些地方都是最缺乏完整觀測資料的區域，因此中央氣象局預計需再花費上千萬之預算購置海上觀測儀器，然而氣象衛星觀測儀器多，觀測區域完整，且資料接收不需花費昂貴之經費，在颱風研究方面的應用便更加顯得重要。對於侵台前之梅雨及颱風降水預報，氣象雷達掃描之區域有限，而模式亦有初始化及參數化之問題，無法很準確地預測短期的強烈降水，故發展被動式微波輻射計估算降水預報是刻不容緩之議題。最近Kidder等(2005)使用SSM/I(Special Sensor Microwave /Imager)、TMI(TRMM Microwave Imager)及AMSU(Advanced Microwave Sounding Unit) 等被動微波儀估算，參考美國官方之颱風最佳路徑，預測豪大雨之24小時潛勢預報，此技術(Tropical Rainfall Potential，TRaP)提供一個快速又實用的方法，應用此方法預測降雨量比中尺度數值預測模式更接近於實際觀測(Ferraro等，2005)。本研究的前期研究曾利用SSM/I 估算梅雨期及颱風降雨量，而陳等(2002)亦使用TMI 及AMSU-A 估算降水，結果與地面之觀測比較都有不錯之結果，故皆可用於颱風降水之估算。就颱風與梅雨降水預測而言，本研究先使用持續法，利用中央氣象局之路徑預測資料，可得到六、十二、二十四小時後之潛勢降水預報，並與地面觀測之累積雨量比較。颱風之生成與發展和海洋所蓄含的能量有相當密切的關係。另本研究亦將探討颱風螺旋雨帶移動與地形效應對降水之影響，將颱風及梅雨預報降水技術提升，並能自動化作業，提供未來對颱風及梅雨降水預報與防災之參考。According to all the tracks of typhoons during the past 50 years, Taiwan is situated in the main path of typhoons originating in the Northwest Pacific Ocean. Taiwan is also located in the region where are easily influenced by the nature disasters. World Bank Annual Report 2005, the Natural Disaster Hotspots - A Global Risk Analysis pointed out that Taiwan were exposed to three or more kinds of natural disasters, potential disaster threats to the population is about 73%, while exposure to two or more kinds of natural disasters threats to the population is 99%. People in Taiwan live at high-risk of disaster in the world. Global climate change rapidly in recent years, the incidence cases of extreme weather disasters increase, such as in the Myanmar of cyclone Nargis (2008) disaster in 2009, Taiwan's typhoon Morakot disasters, 2010 floods in Pakistan and 2010 floods in California, The scale of disasters and extreme rainfall exceeded the country's history records of disaster experience, but also the loss of the governments and people of the country. Pursue of better accuracy of quantitative precipitation forecast is always a scientific study goal, especially for disastrous rainfall from landing typhoons and Mei-Yu fronts. Typhoons get birth and develop on ocean where traditional observations are scarce. Satellite observation data are very crucial to tropical cyclone’s monitoring. While the typhoons are approaching offshore, fewer traditional observations around typhoons are available. Radar observations of rainfall structures are although valuable, but only could be used for landing typhoon observation. Satellite-borne microwave radiometers can measure instantaneous rain rates through the entire cloud area of typhoons which more suitable for usage on rainfall forecast. This study uses SSM/I data to estimate typhoon precipitation. Chen, et al. (2002) had used TMI and AMSU-A data to estimate MEI-YU rainfall. It showed a good relationship between ground truths and estimations. Another microwave radiometer AMSR-E, one of AQUA instruments which were launched in Jun 2002, will be added to estimate the rainfall of Northwest Pacific’s typhoons. According to original Tropical Rainfall Potential (TRaP), it is assumed that estimated rain rates are correct and no change happened on the intensity and rain area size during typhoon movements. First we use JTWC’s typhoon best track data to predict rainfall potential of 3, 6, 12 and 24-hour forecast. The results are validated through rain gauges data. The second, air-sea parameters will be added to estimate the intensity and rainfall change of typhoons or Mei- Yu fronts, and further be applied to predict rainfall potential. Finally terrain effect will be considered to estimate the Mei-Yu and typhoon precipitation 研究期間：10008 ~ 10107 |
